Transient activation of biochemical reactions by visible light and subsequent return to the inactive state in the absence of light is an essential feature of the biochemical processes in photoreceptor cells. To mimic such light-responsiveness with artificial nanosystems, polymersome nanoreactors were developed that can be switched on by visible light and self-revert fast in the dark at room temperature to their inactive state. Donor-acceptor Stenhouse adducts (DASAs), with their ability to isomerize upon irradiation with visible light, were employed to change the permeability of polymersome membranes by switching polarity from a nonpolar triene-enol form to a cyclopentenone with increased polarity. To this end, amphiphilic block copolymers containing poly(pentafluorophenyl methacrylate) in their hydrophobic block were synthesized by reversible addition-fragmentation chain-transfer (RAFT) radical polymerization and functionalized either with a DASA that is based on Meldrum's acid or with a novel fast-switching pyrazolone-based DASA. These polymers were self-assembled into vesicles. Release of hydrophilic payload could be triggered by light and stopped as soon as the light was turned off. The encapsulation of enzymes yielded photoresponsive nanoreactors that catalyzed reactions only if they were irradiated with light. A mixture of polymersome nanoreactors, one that switches in green light, the other switching in red light, permitted specific control of the individual reactions of a reaction cascade in one pot by irradiation with varied wavelengths, thus enabling light-controlled wavelength-selective catalysis. The DASA-based nanoreactors demonstrate the potential of DASAs to switch permeability of membranes and could find application to switch reactions on and off, on demand, e.g., in microfluidics or in drug delivery.

中文翻译：

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波长选择性光响应 DASA 功能化聚合物纳米反应器

可见光对生化反应的瞬时激活和随后在没有光的情况下返回到非活动状态是感光细胞生化过程的基本特征。为了模拟人工纳米系统的这种光响应性，开发了聚合物纳米反应器，可以通过可见光打开，并在室温下在黑暗中快速自我恢复到非活动状态。供体-受体 Stenhouse 加合物 (DASA) 具有在可见光照射下异构化的能力，通过将极性从非极性三烯-烯醇形式转换为极性增加的环戊烯酮来改变聚合物膜的渗透性。为此，通过可逆加成断裂链转移 (RAFT) 自由基聚合合成了疏水嵌段中含有聚甲基丙烯酸五氟苯酯的两亲性嵌段共聚物，并使用基于 Meldrum 酸的 DASA 或新型快速转换吡唑啉酮基进行官能化。达萨。这些聚合物自组装成囊泡。亲水有效载荷的释放可以由光触发并在光关闭后立即停止。酶的封装产生了光响应纳米反应器，只有在用光照射时才能催化反应。聚合物纳米反应器的混合物，一个在绿光下切换，另一个在红光下切换，允许通过不同波长的照射在一个锅中特定控制反应级联的各个反应，从而实现光控波长选择性催化。基于 DASA 的纳米反应器展示了 DASA 切换膜渗透性的潜力，并且可以应用于按需切换反应的开启和关闭，例如在微流体或药物输送中。